Method for manufacturing a cell-driving-type micro pump member

ABSTRACT

A method for manufacturing a micro pump member, in which a plurality of cells formed in a base part are used as pressurizing chambers, and side walls forming the pressurizing chambers are constructed by piezoelectric/electrostrictive elements. The micro pump member is formed by using a punch and die to form slits through green sheets that are laminated to one another.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of U.S. Ser. No. 09/900,742 filed on Jul.6, 2001 now U.S. Pat. No. 6,699,018, issued Mar. 2, 2004, the entiretyof which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a cell-driving-type micro pump memberbased on the piezoelectric/electrostrictive effect, more specifically,to a cell-driving-type micro pump member having a high response andproviding a high pressurizing force. The micro pump includes separatecells whose side walls are made of piezoelectric/electrostrictiveelements. Each cell is used as a pressurizing chamber, so that apressure can be produced in the pressurizing chamber by changing thevolume of the cell with the aid of the displacement of thepiezoelectric/electrostrictive elements.

Recently, mechanisms providing a change of volume in a pressurizingchamber by deforming a part of the walls forming the pressurizingchamber with the aid of the piezoelectric/electrostrictive effect areknown, where the mechanism increases the pressure in a smallpressurizing chamber formed in a base part. Such a micro pump member isused, for instance, as an ink pump member or the like in a print headused in an ink jet printer, wherein the pressure in the pressurizingchamber, to which ink is supplied and then stored therein, is increasedby the displacement of the piezoelectric/electrostrictive elements, sothat the ink particles (droplets) are ejected from nozzle holesconnected to the pressurizing chamber, and thus the printing can becarried out.

For instance, in JP-A-6-40030, an example of an ink jet print head asshown in FIG. 16 and FIG. 17 is described, wherein a micro pump memberis used as an ink pump member. The ink jet print head 140 is formed byjoining an ink nozzle element 142, an ink pump member 144 and apiezoelectric/electrostrictive element 178 to each other, to form aunified body. The ink, which is supplied to ink pressurizing chambers146 (hereafter simply referred to as pressurizing chambers), is ejectedthrough nozzle holes 154 in the ink nozzle member 142 by the bendingdeformation of a closing plate 166 (vibration plate) forming thepressurizing chamber 146 in accordance with the deformation of thepiezoelectric/electrostrictive element 178, thus inducing a pressure inthe pressurizing chamber 146.

The ink pump member 144 is formed as a unified body, in detail, withsuch a construction that the closing plate 166 and a connecting plate168, each of which has a planar shape, are superimposed on each othersandwiching a spacer blade 170 therebetween. In the connecting plate168, first connecting openings 172 and second connecting openings 174are respectively formed at the positions corresponding to through-holes156 and orifice holes 158 which are formed in an orifice plate 150 ofthe ink nozzle element 142. Moreover, a plurality of rectangle-shapedwindow parts 176 is formed in the spacer plate 170. The spacer plate 170is superimposed on the connecting plate 168 in such a manner that eachof the first connecting openings 172 and second connecting openings 174,which are disposed in the connecting plate 168 is opened to thecorresponding window parts 176. In this spacer blade 170, moreover, theclosing plate 166 is superimposed on the surface opposite that on whichthe connecting plate 168 is superimposed, so that the openings of thewindow parts 176 are closed at the closing plate 166. By so doing, thepressurizing chambers 146, which are connected to the outside via thefirst and second connecting openings 172, 174, are formed in the insideof the ink pump member 144.

In such an ink jet print head 140, however, there are the followingproblems. In order to provide a greater displacement so as to be able toeject a greater number of droplets, it is effective to decrease thethickness of the closing plate 166 (vibrating plate) in the ink pumpmember 144. However, this induces a decrease in the rigidity and reducesthe high responsiveness. On the other hand, a significant enhancement inthe high responsiveness requires an increase in the rigidity. For thispurpose, it would be effective to increase the thickness of the closingplate 166 (vibrating plate), but this treatment provides a reduceddisplacement, thereby making it impossible to eject the required numberof droplets. That is, in the ink pump member, it is difficult to attainboth a greater displacement and a higher response property by thebending deformation of the vibrating plate due to the displacement ofthe piezoelectric/electrostrictive element. This is the first problem.

As for the second problem, it has been found that if one wants to makethe adjacent ink pump members the same action, the displacement isreduced compared with the case where the piezoelectric/electrostrictiveelement is singly driven; this results in failure to display theintrinsic characteristics. That is, the vibrating plates of two adjacentink pump members are bent simultaneously, so that a pulling force isapplied to the walls between the ink pump members, thereby making itdifficult to bend the vibrating plates.

Although not shown in the drawings, it has been proposed inJP-A-6-350155 that the interference due to the mutual displacement ofthe piezoelectric/electrostrictive elements is suppressed by disposing agroove between a concave part (ink pressurizing chamber) and theadjacent concave part, that is, by disposing a groove between adjacentink pump members.

Moreover, as for a micro pump member based on the knownpiezoelectric/electrostrictive effect, for instance, a micro pumpmember, which is driven in shear mode and is similarly used in an inkjet head, is employed. This is a micro pump 271 having such a structureas shown in FIG. 7, wherein a plurality ofpiezoelectric/electrostrictive elements as comb teeth 276, that is,driving parts 274, are arranged like teeth of a comb on a base plate272, and cells 273 having substantially rectangular form are formed by aclosing slit 275 between the comb teeth with a cover plate 277. Theopenings at the front end of the micro pump member 271 are closed by anozzle plate 9 having nozzles 8, so that an ink jet head 270 is formedso as to use the cells 273 as pressurizing chambers. By applying adriving electric field in a direction vertical to the direction ofpolarizing field in the driving parts 274, that is, comb teeth 276,consisting of the piezoelectric/electrostrictive material, the combteeth 276 are deformed and thus the volume of the cells 273 are changed,thereby enabling the ink stored in the cells 273 to be ejected.Furthermore, the method of driving where the displacement results fromthe driving electric field in the direction vertical to the direction ofpolarization in the piezoelectric/electrostrictive elements is calledthe shear mode method.

Such a micro pump member 271 is manufactured according to the stepsshown in FIG. 8( a)-FIG. 8( e). Firstly, apiezoelectric/electrostrictive material 86 is provided as shown in FIG.8( a), and fired in FIG. 8( b). In FIG. 8( c), the polarizationtreatment is carried out and in FIG. 8( d), fine slits are formed with adicing saw or the like, and driving parts 274 are arranged like theteeth of a comb in a regular form by interposing therebetween aplurality of slits 275 corresponding to respective spaces for storingthe ink, and then electrodes are formed on the wall surfaces in theslits 275 in FIG. 8( e). After that, as shown in FIG. 7, the cover plate277 comprising a glass plate or the like is mounted, and then theopenings at the front end of the comb teeth are closed with the nozzleplate 9 having the nozzles 8, so that the cells 273 used as thepressurizing chambers are formed.

In such a manufacturing method, however, there are the followingproblems due to machining rigid, fired piezoelectric/electrostrictivematerials. The first problem is that it is time-consuming to machine theslits with the dicing saw or the like, and therefore it is unsuitablefor mass production.

Furthermore, the second problem is the cost increase. This is becausesufficient cleaning is required after machining since the products arepolluted with the free grinder particles for processing and the processliquid; this would require complex cleaning processes to clean them in asatisfactory manner due to the reduced strength after machining, withnecessarily accompanying the process for drying, and facilities for bothtreating water for cleaning and exhausted water and the managementthereof as well.

The third problem is that the slits forming the cells used aspressurizing chambers are restricted by the thickness of the dicingblade used for machining, so that a width of approximately 60 μm or lesscannot be realized. Additionally, the thickness of the comb teeth, thatis, the driving parts, also has a limitation regarding the depth of theslits so that the required grinding force for the dicing blade isobtained, and it is difficult to form cells or pressurizing chambershaving a high aspect ratio of, for example, 10 or more, so that it isdifficult to obtain a high power micro pump member having a high densityor a high strength.

Generally, the aspect ratio is denoted by the ratio of the diameter tothe axial length, in the case of an aperture having a cylindrical form.If the aperture has a non-cylindrical form, such as that shown in FIG.8( d), i.e., in the case of the slit 275, which is later closed and thusbecomes a cell (pressurizing chamber), the aspect ratio is denoted bythe ratio of the shortest spacing between two comb teeth forming theslit 275, the comb teeth facing each other, that is, the width of theslit 275 to the depth of the slit 275. A pressurizing chamber having ahigh aspect ratio implies a pressurizing chamber whose height is greatercompared with the inside width.

The fourth problem is that machining with a dicing blade only allows theproduction of straight and flat slits, so that a subsequent process foradhering parts is required if one wants the cells (the pressurizingchamber), to have a complex form. Moreover, since electric stressdeformation rises up to the joint end of the slit plates when activatedas a result of the straight machining, the durability of the jointsurfaces is liable to be reduced therefrom.

The fifth problem is that, since the slit is formed with the grindingprocess after firing, micro cracks and fractures inside the grains ofthe piezoelectric/electrostrictive particles often occur at the sidesurface of the comb-like driving parts 274, and the characteristics ofthe cells are liable to be deteriorated. FIG. 9( a) and FIG. 9( b) aredrawings illustrating this fact: FIG. 9( a) is a side view from Q inFIG. 8( d) and FIG. 9( b) is a magnified section of part N in FIG. 9(a). In the case of the grinding process with the dicing saw, eithermicro cracks from the machining or particles fractured in the grainsresult, on the side surface of comb-like driving parts 274 (teeth 276 ofa comb), the particles thus have deteriorating properties, so that whenthe cell is driven, the performance inherent in the material cannot beobtained, and the micro cracks propagate, thereby damaging the deviceitself.

In the conventional micro pump member 271, moreover, problems occur as aresult of the driving in the shear mode. The sixth problem is that afterfiring and carrying out the polarizing treatment, manufacturingprocesses involving heating to a temperature of the Curie temperature orhigher caused the polarization in the piezoelectric/electrostrictivematerial and cannot be applied. As a result, in the case offixing/wiring the micro pump members to a circuit board, the solderingprocess using the reflow-soldering method or adhesion under heatingcannot be applied, due to the thermal restriction, and the throughput isreduced, thereby increasing the cost of manufacturing. Moreover, eitherlaser machining or machining generating heat is also restricted.

Moreover, as for the seventh problem, it is noted that since the drivingelectric field is generated in the direction vertical to the directionof polarization field, activation with a high field strength, whichcauses the change in the state of polarization, is not permitted, sothat a greater amount of strain cannot be obtained. If, however, a highdriving electric field is generated, the state of polarization graduallychanges during the driving period, hence, similarly reducing the amountof strain. As a result, the basic performance of the micro pump memberdeteriorates.

Moreover, in the conventional micro pump member 271, problems occur as aresult of the structure in which the base plate, driving parts and coverplate are unified into one body, along with the problems which occur asa result of the above-mentioned manufacturing method, that is, theproblem due to driving in the shear mode.

The eighth problem is the difficulty in making the adjacent cells(pressurizing chambers) in the same action. FIG. 15 is a sectional viewshowing the states of deactivation and activation for the micro pumpmember 271 as an example. When the driving electric field is applied,that is, in the case of the OFF state, the driving parts 274 of thepiezoelectric/electrostrictive elements are not deformed, whereas whenthe driving electric field is applied to a specified driving part 274,that is, in the case of the ON state, the driving part 274 is deformed.As can be seen in FIG. 15, the driving part 274 acts as the drivingelements for two cells 273, so that when the volume of the one cellincreases, the volume of the adjacent cells decreases. When, forinstance, the micro pump member 271 is used as the ink jet head 270shown in FIG. 7, ink cannot be simultaneously ejected from the adjacentcells, that is, the pressurizing chambers. As a result, at least twoactions are required to spray ink to an article to be sprayed in theminimum spacing between the ink jet head and the article. This isundesirable in view of enhancing speed in the ink ejecting process.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, an object of the presentinvention is to provide a micro pump member and a method formanufacturing the micro pump member, wherein a heating process at ahigher temperature can be applied; mass production can be carried out atlow cost; slit parts have cells having a shape inclusive of any shapeother than shapes defined by straight lines; the slit parts have cellswhose width is 60 μm or less, and the cells have a high aspect ratio; anactivation with a high field strength is feasible; furthermore, agreater displacement and a higher response can be attained with asmaller field strength.

After studying micro pump members and the methods for manufacturing themember, it was found that the objects can be attained by the micro pumpmember and the manufacturing method described below.

Namely, the present invention provides a cell-driving-type micro pumpmember wherein a plurality of cells formed in the inside of a base partis used as pressurizing chambers, the side walls forming thepressurizing chambers are constituted by thepiezoelectric/electrostrictive elements, a pressure in the cells isproduced by changing the volume of the pressurizing chambers due to thedisplacement of the piezoelectric/electrostrictive elements,characterized in that the pressurizing chambers are formed independentlyof the adjacent pressurizing chambers.

In the cell-driving-type micro pump member according to the invention,it is desirable that the base part comprises a spacer plate consistingof the piezoelectric/electrostrictive elements in which a plurality ofslits A are formed, a cover plate covering slits A on one side of thespacer plates, and a connecting plate covering the slits A on the otherside of the spacer plates, wherein slits B, which pass through the coverplates and spacer plates, are formed between a slit A and the adjacentslits A.

Moreover, it is desirable that the polarizing field of thepiezoelectric/electrostrictive elements and the driving electric fieldare aligned in the same direction. It is desirable that electrode layersare formed on both surfaces of side walls forming respectivepressurizing chambers, and the side walls are expanded or constricted inthe upward or downward direction by applying a voltage to the electrodelayers.

In the cell-driving-type micro pump member of the present invention, itis desirable that the transgranular fracture of crystal grains is 1% orless, and the degree of profile for the surfaces of the pressurizingchambers is approximately 8 μm or less. Moreover, it is desirable thatthe ratio of the inside width to the height of the pressurizing chamberis approximately 1:2-1:40, and the ratio of the spacing between thepressurizing chamber and the adjacent chamber and the height of thepressurizing chamber is approximately 1:2-1:40.

Moreover, it is desirable that the inside width of the pressurizingchamber is approximately 60 μm or less, and that the spacing between thepressurizing chamber and the adjacent pressurizing chamber isapproximately 50 μm or less. It is desirable that the surface roughnessRt of side walls forming the pressurizing chamber is approximately 10 μmor less.

In the cell-driving-type micro pump member of the present invention, itis desirable that, in accordance with the application, there may existat least two distances different from each with respect to the insidewidth of the pressurizing chambers or the spacing between thepressurizing chamber and the adjacent chamber. Moreover, it is desirablethat the pressurizing chambers have a reservoir at least at one axialend of the cell.

According to the present invention, a liquid discharging device isprovided, including a cell-driving-type micro pump member used therein,wherein a liquid connecting opening is disposed on one surface of thepressurizing chambers and a liquid supplying opening is disposed at theother surface of the pressurizing chambers, and a liquid nozzle memberhaving a plurality of nozzle holes for discharging the particlesconsisting of droplets is superimposed on one side of thecell-driving-type micro pump member in such a manner that the nozzleholes are connected to the pressurizing chambers. When a drivingelectric field is applied in the same direction as that of thepolarizing field of the piezoelectric/electrostrictive elements, thepressurizing chambers are deformed by expanding/contracting the sidewalls of the pressurizing chambers consisting ofpiezoelectric/electrostrictive elements in the upward/downwarddirection, so that the liquid supplied to the pressurizing chambers canbe discharged from the nozzle holes to one side.

Moreover, a liquid discharging device is provided, including acell-driving-type micro pump member used therein, wherein a liquidsupplying opening and a liquid connecting opening are disposed on onesurface of the pressurizing chambers. A liquid supplying channel isconnected to the liquid supplying opening on one surface of thecell-driving-type micro pump member, and a liquid nozzle member having aplurality of nozzle holes for discharging the particles of droplets issuperimposed on one surface in such a manner that the nozzle holes areconnected to the pressurizing chambers. When a driving electric field isapplied in the same direction as that of the polarizing field of thepiezoelectric/electrostrictive elements, and the pressurizing chambersare deformed by expanding/contracting the side walls of the pressurizingchambers consisting of piezoelectric/electrostrictive elements in theupward/downward direction, the liquid supplied to the pressurizingchambers can be discharged from the nozzle holes to one side.

In the liquid discharging device, it is desirable that one surface ofthe pressurizing chambers is the lower surface and the other surface ofthe pressurizing chambers is the upper surface, and the liquid suppliedto the pressurizing chambers can be discharged from the nozzle holes inthe direction toward the lower surface.

Furthermore, two methods for manufacturing the cell-driving-type micropump member according to the present invention are provided, as shownbelow. The first manufacturing method is a method for manufacturing thecell-driving-type micro pump member using a punch and a die, wherein thepressurizing chambers which are a plurality of cells formed in theinside of a base part, and whose side walls comprisepiezoelectric/electrostrictive elements, are formed to be independent ofthe adjacent pressurizing chambers. The first method is characterized inthat it comprises the steps of; providing a plurality of green sheetsmade of piezoelectric/electrostrictive elements; positioning and thenlaminating all the green sheets after slit apertures are machined in allthe green sheets (denoted by the lamination after punching); and formingpiezoelectric/electrostrictive elements in which a plurality of slitsare formed.

The second manufacturing method is a method for manufacturing thecell-driving-type micro pump member using a punch and a die, wherein thepressurizing chambers which are a plurality of cells formed in theinside of a base part, and whose side walls comprisepiezoelectric/electrostrictive elements, are formed to be independent ofthe adjacent pressurizing chambers. The second method is characterizedin that it comprises the steps of, providing a plurality of green sheetsmade of piezoelectric/electrostrictive elements; performing a first stepfor machining first slit apertures in the first green sheet with thepunch, a second step for moving the first green sheets upwards intotight contact with a stripper in the state of the punch not beingwithdrawn from the first slit apertures, and a third step for moving thepunch upwards in such a way that the front end of the punch is withdrawnslightly from the lowest part of the first green sheet moved upwards;performing a fourth step for machining second slit apertures in thesecond green sheet, a fifth step for moving the second green sheetupwards together with the first green sheet in the state of the punchnot being withdrawn, and a sixth step for moving the punch upwards insuch a way that the front end of the punch is slightly withdrawn fromthe lowest part of the second green sheet moved upwards; then,laminating the green sheets by repeating the fourth step to the sixthstep (denoted by the simultaneous punch and lamination), and thenforming piezoelectric/electrostrictive elements in which a plurality ofslits is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a) and 1(b) are sectional views of an embodiment of acell-driving-type micro pump member according to the invention.

FIGS. 2( a) and 2(b) are sectional views of the embodiment of acell-driving-type micro pump member according to the invention(activation state).

FIGS. 3( a) to 3(c) are schematic drawings showing an embodiment of aprocess in a method for manufacturing a cell-driving-type micro pumpmember according to the invention.

FIGS. 4( a) to 4(c) are schematic drawings showing another embodiment ofthe process in a method for manufacturing a cell-driving-type micro pumpmember according to the invention.

FIGS. 5( a) and 5(b) are drawings showing a second method formanufacturing a cell-driving-type micro pump member according to theinvention, including the simultaneous punching and lamination; FIG. 5(a) is a side view from P in FIG. 4( b), and FIG. 5( b) schematicallyshows an magnified section of part M in FIG. 5( a).

FIGS. 6( a) to 6(e) are drawings explaining an embodiment of the processfor simultaneously punching and laminating the green sheets shown inFIG. 4( a); FIG. 6( a) shows a preparation step for laying a first greensheet on the die; FIG. 6( b) shows a step for punching the first greensheet; FIG. 6( c) shows a preparation process for laying a second greensheet on the first green sheet; FIG. 6( d) shows a step for punching thesecond green sheet; and FIG. 6( e) is a drawing showing a final punchingcompleting step for punching all the sheets, completing the laminationand removing the laminated green sheets with a stripper.

FIG. 7 is a perspective view of an embodiment of an ink jet headequipped with a conventional micro pump member.

FIGS. 8( a) to 8(e) are schematic drawings for explaining an embodimentof a method for manufacturing a conventional micro pump member.

FIGS. 9( a) and 9(b) are drawings showing the conventional method formanufacturing a cell-driving-type micro pump member shown in FIG. 8(a)-FIG. 8( e); FIG. 9( a) is a side view from Q in FIG. 8( d), and FIG.9( b) schematically shows a magnified section of part N in FIG. 9( a).

FIGS. 10( a) to 10(c) are sectional views of an embodiment of acell-driving-type micro pump member according to the invention.

FIG. 11 is a sectional view of an embodiment of a cell-driving-typemicro pump member according to the invention, which is applied to aliquid discharging device, where the cell width and the spacing betweenthe cells are respectively not the same, but with at least two differentdistances.

FIGS. 12( a) to 12(c) are schematic drawings showing a process in ananother embodiment of a method for manufacturing a cell-driving-typemicro pump member according to the invention.

FIGS. 13( a) to 13(c) are schematic drawings showing a process in ananother embodiment of a method for manufacturing a cell-driving-typemicro pump member according to the invention.

FIG. 14 shows sectional views of an embodiment of a cell-driving-typemicro pump member according to the invention in the deactivated andactivated states.

FIG. 15 shows sectional views of an embodiment of a micro pump member ofthe conventional art in the deactivated and activated states.

FIG. 16 is a sectional view of an embodiment of a micro pump member inthe conventional art.

FIG. 17 is a sectional view of another embodiment of a micro pump memberof the conventional art, and shows a sectional view from AA′ in FIG. 16.

FIGS. 18( a) to 18(e) are drawings showing an embodiment of a processfor manufacturing a cell-driving-type micro pump according to theinvention by utilizing the conventional manufacturing method.

FIG. 19 is a sectional drawing showing another embodiment of acell-driving-type micro pump according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Next, referring to the drawings, various embodiments will bespecifically explained regarding a cell-driving-type micro pump memberand a method for manufacturing the micro pump member. However, thepresent invention is not restricted to the above. Various changes,revisions and modifications are possible on the basis of the knowledgeof a person skilled in the art, unless these are outside of the scope ofthe invention. In the description, moreover, activating the micro pumpmember means driving at least one cell, i.e., producing a pressure in apressurizing chamber. Producing a pressure in the pressurizing chambermeans that the driving parts, i.e., side walls consisting of thepressurizing chambers, are deformed by applying a driving electric fieldthereto, thereby inducing a change in the volume of the pressurizingchambers and thus providing a pressurized state or a depressurized statein the pressurizing chambers.

FIG. 1( a), FIG. 1( b), FIG. 2( a), and FIG. 2( b) are sectional viewsof an embodiment of a cell-driving-type micro pump member according tothe present invention. FIG. 1( a) shows a longitudinal section of apressurizing chamber 46 in the cell-driving-type micro pump member 44,and FIG. 1( b) shows a transverse section of the pressurizing chamber 46in the cell-driving-type micro pump member 44. FIG. 2( a) and FIG. 2( b)show longitudinal and transverse sections in the activated state.

In the cell-driving-type micro pump member 44, a plurality of cells 3formed inside a base part 2 is used as the pressurizing chambers 46, andside walls 6 forming the pressurizing chambers 46 are constituted bypiezoelectric/electrostrictive elements, and a pressure is produced inthe pressurizing chambers 46 by changing the volume of the pressurizingchambers 46 with the aid of the displacement of thepiezoelectric/electrostrictive elements.

The base part 2 can be formed by a spacer plate 70 of thepiezoelectric/electrostrictive elements forming a plurality of slits 5,a cover plate 7 covering the slits 5 on one side of the spacer plate 70,and a connecting plate 68 covering the slits 5 on the other side of thespacer plate 70. And, a slit 45 passing through the cover plate 7 andthe spacer plate 70 is formed between one of the slits 5 and theadjacent slit 5 of the base part 2. The cell 3, that is, a pressurizingchamber 46, is formed by the slit 5 and the cover plate 7. Two adjacentpressurizing chambers 46 are isolated from each other by the slit 45.

For instance, a liquid connecting opening 72 is disposed on one surfaceof the pressurizing chamber 46 of the cell-driving-type micro pumpmember 44, and a liquid supplying opening 64 is disposed on the othersurface of the pressurizing chamber 46. The liquid discharging device 40is constructed by adjusting the position of the liquid connectingopening 72 with respect to a nozzle hole (hereafter denoted as a nozzle)with a liquid nozzle member 42 having nozzle holes in such a way thatthe nozzle holes are connected to the pressurizing chamber 46. Sidewalls 6 of the pressurizing chamber 46 made ofpiezoelectric/electrostrictive elements are expanded/constricted in theup/down direction by applying a driving electric field in the samedirection as that of the polarizing field of thepiezoelectric/electrostrictive elements. Thus, the pressurizing chamber46 is deformed, so that the liquid supplied to the pressurizing chamber46 can be discharged from the nozzle hole towards the side of onesurface. The liquid nozzle member 42 can be a nozzle plate 9 havingnozzles 8. In FIG. 1( a) and FIG. 1( b), it is shown that, for instance,one surface is the under face, and the other surface is the top face.

The liquid discharging device 40 can be employed in, for instance, ahead of an ink jet printer, a micro droplet discharging apparatus usedin the mixing and reaction treatment of a liquid of a small volume inthe field of biotechnology, in the manufacturing of DNA chips necessaryfor analyzing the structure of a gene and in the coating process forsemiconductor manufacturing, or an apparatus for spraying fuel, rawmaterials, etc.

In the cell-driving-type micro pump member 44 according to the presentinvention, a characteristic lies in the point that the pressurizingchamber 46 is formed independently of the adjacent pressurizing chamber46 via the slit 45 without employing such a structure that thevolume-changeable cells, that is, pressurizing chambers, are formed by acommon cover plate, and a driving part is used as a driving part for twocells like in the case of the conventional micro pump member 271 asshown in FIG. 7.

A further characteristic lies in the point that the polarization fieldof the piezoelectric/electrostrictive elements constituting the sidewalls 6, that is, driving parts for the pressurizing chamber 46, isaligned in the same direction as that of the driving electric field.Moreover, a further characteristic lies in the point that electrodelayers are formed on both sides of the side walls 6 forming thepressurizing chamber 46, and the side walls 6 are expanded/constrictedin the up/down direction by applying a voltage to the electrode layers,without generating pressure by bending a closing plate (vibratingplate), that is, the upper wall constituting the pressurizing chamber,like as an ink pump member 144 as shown in FIG. 16.

As shown in FIG. 1( a) and FIG. 1( b), the slit 45 is formed between thepressurizing chamber 46 and the adjacent pressurizing chamber 46, sothat these pressurizing chambers 46 are formed so as to be independentof one another. Due to this structure, the pressurizing chambers 46 canbe activated independently of the other pressurizing chambers 46. Inaddition, the same action can be obtained for the adjacent pressurizingchambers 46, thereby enabling the piezoelectric/electrostrictiveelements to be driven without being interfered with each other.Moreover, the slit 45 can be formed between adjacent pressurizingchambers 46 in such a manner that it does not disturb the deformation ofdriving parts 4, that is, the side walls 6. For instance, as can betaken from the activated state in FIG. 2( a), the slit 45 can be formedsuch that the slit 45 has substantially the same length as that of atleast the deformable part of the cover plate 7 in the axial direction ofthe pressurizing chamber 46. More preferably the slit 45 is formed tohave the same length as that of the pressurizing chamber 46.

FIG. 14 shows sectional views of the cell-driving-type micro pump member44 according to the invention in the deactivated and activated states.When no driving electric field is applied, that is, in the OFF state,the driving parts of the piezoelectric/electrostrictive elements are notdeformed, whereas when a driving electric field is applied to aspecified driving part 4, the driving part 4 is deformed. In this case,the pressurizing chambers 46, that is, the cells 3, are formed in thebase part 2 so as to be separated from each other via the slit 45.Accordingly, the activation of the pressurizing chamber 46 and theactivation of the adjacent pressurizing chamber 46 can be performedindependently of each other without any restriction regarding the amountof deformation, thereby enabling the same action to be conducted for twoadjacent pressurizing chambers 46, as shown in FIG. 14. As a result, asmaller field strength is required to obtain the same amount ofdeformation.

Moreover, the deformation, that is, the expansion/compression of theside walls 6, that is, the driving parts 4, provides a change in thevolume of the pressurizing chamber 46, thus producing a pressure. As aresult, it is unnecessary to form the driving parts 4 in a thin form inorder to obtain a greater deformation, and there is no problem regardingthe fact that a possible reduction of the response results from thereduced rigidity. A greater deformation and higher response can beattained without any sacrifice of either.

When, for instance, the cell-driving-type micro pump member 44 is usedas the above-mentioned liquid discharging device 40, liquid can besimultaneously discharged from adjacent pressurizing chambers. Sinceliquid can be ejected to an article to be sprayed with a minimum spacingbetween the device and the article, the frequency of activation for thepressurizing chambers can be reduced, compared with those in theconventional art, thereby enhancing the rate of liquid discharge. If,for instance, the liquid discharging device 40 is employed in aproduction line of DNA chips, the cost of production can be greatlyreduced.

Moreover, since the polarizing field of thepiezoelectric/electrostrictive elements is aligned in the same directionas that in the driving electric field, it is not necessary to producetemporary or dummy electrodes for the polarization, or to apply anelectric field thereto, thereby enhancing the throughput. Moreover,irrespective of the polarizing treatments, it is possible to employ amanufacturing process in which heating at a temperature of the Curietemperature or higher is carried out. Accordingly, in the case offixing/wiring the micro pump member to, e.g., a circuit board, solderingwith reflow solder or thermosetting adhesion are feasible, so that,inclusive of the process for manufacturing a product in which the micropump member is used, the throughput can further be enhanced, thusreducing the cost of production.

Moreover, even if an electric field having a high strength is applied tothe driving parts, the state of polarization is not changed, rather amore desirable state of polarization can be obtained. Therefore, becausea compact product can be obtained, it is desirable to use it as a micropump member.

In the cell-driving-type micro pump member 44, it is desirable that thedegree of profile for the surface of the side walls forming thepressurizing chamber is approximately 8 μm or less. It is desirable thatthe unevenness of the wall surface of the side walls forming thepressurizing chamber is approximately 10 μm or less. Moreover, it isdesirable that the surface roughness Rt of the wall surface of the sidewalls forming the pressuring chamber is approximately 10 μm or less. Themicro pump member fulfilling at least one of these conditions has asmooth surface for the side walls or driving parts forming thepressurizing chamber on the inside thereof, thereby neither theconcentration of field nor the concentration of the stress arises, thusenabling a stable discharge operation to be performed for the respectivepressurizing chambers.

In conjunction with the above, the degree of profile for a surface isgiven in Japanese Industrial Standard B0621: “the definition andrepresentation of the geometrical deviation.” The profile of a surfaceis a surface having a functionally specified shape, and the degree ofprofile for a surface is defined as the deviation of the surface contourfrom a geometrical contour, which is determined by a theoreticallyspecified exact dimension. In the present invention, the surface of acell implies the inside cell wall surface of the driving parts composingthe cell.

In the cell-driving-type micro pump member 44 shown in FIGS. 1( a) and1(b), the ratio of the inside width W to the height H of thepressurizing chamber, in other words, the aspect ratio W:H of thepressurizing chamber, is preferably approximately 1:2 to 1:40, and theinside width W of the pressurizing chamber is preferably approximately60 μm or less. More preferably, the aspect ratio W:H of the pressurizingchamber is 1:10 to 1:25, and the inside width of the pressurizingchamber is 50 μm or less. The reason why those values are preferable isthat the danger of dielectric breakdown would increase since a fieldsufficient to obtain a greater pressure would become too high if theaspect ratio is small, whereas the occurrence of defective productswould increase during the assembling and handling period since themechanical strength would decrease if the aspect ratio increases. Amicro pump member fulfilling at least one of these conditions ispreferred, and more preferably, a micro pump member fulfilling the twoconditions is preferred, in other words, a thinner micro pump memberhaving a greater height can easily provide a higher power with a higherdensity, thereby a more compact micro pump member can be realized.

Moreover, in the cell-driving-type micro pump member 44 shown in FIGS.1( a) and 1(b), the ratio of the spacing between the pressurizingchamber and the adjacent pressurizing chamber to the height of thepressurizing chamber is preferably approximately 1:2 to 1:40, and thespacing between the pressurizing chamber and the adjacent pressuringchamber, that is, the spacing between pressurizing chambers ispreferably approximately 50 μm or less. More preferably, the ratio ofthe spacing between the pressurizing chamber and the adjacentpressurizing chamber to the height of the pressurizing chamber is 1:10to 1:25, and the spacing between pressurizing chambers is 30 μm or less.A micro pump member fulfilling at least one of these conditions ispreferred, and more specifically a micro pump member fulfilling the twoconditions is preferred, and includes a greater number of pressurizingchambers, although the pressurizing chamber and the adjacent pressuringchamber can be independently activated, thereby realizing a more compactmicro pump member.

As a result, if the cell-driving-type micro pump member 44 according tothe invention is used as, e.g., the liquid discharging device 40, theliquid can be simultaneously discharged from the adjacent pressurizingchambers 46, and can be ejected to an article to be sprayed at a higherdensity, compared with a conventional micro pump member having astructure where the driving part acts as a driving part for two cells.

In the cell-driving-type micro pump member according to the invention,the shape of the pressurizing chamber is not restricted. FIGS. 10(a)-10(c) are sectional views of an embodiment of a cell-driving-typemicro pump member according to the invention. FIG. 10( a) shows alongitudinal section of a pressurizing chamber 346 of thecell-driving-type micro pump member 44, FIG. 10( b) shows a transversesection of the pressurizing chamber 346 of the cell-driving-type micropump member 44, and FIG. 10( c) shows a horizontal section of the spacerplate 70 constituting the base part 2 of the cell-driving-type micropump member 44. As can be taken from FIG. 10( c), it is also preferablethat the pressurizing chamber 346 has reservoirs 50 at the axial ends.When a liquid discharging device 100 is constructed together with aliquid nozzle member 42 using the cell-driving-type micro pump member44, the reservoirs 50 provide a tolerance regarding the positionaldeviation in adjusting the micro pump member with respect to the inkpump member, which is a problem encountered, in particular, when finedesign of the member is necessary. An increased effect can be providedby having one reservoir 50 disposed at an end at least on the side ofnozzle hole. If, however, the reservoirs 50 are disposed at both ends, amuch more marked effect can be obtained in the case of designing in thatfine holes requiring a high precision positioning are disposed on theliquid supplying side.

Next, the cell-driving-type micro pump member according to the inventionis further described with examples of application, referring to thedrawings. FIG. 11 is a sectional view of an embodiment of thecell-driving-type micro pump member according to the invention, which isapplied to a liquid-discharging device. The inside width of thepressurizing chamber 46, and the spacing between the pressurizingchamber 46 and the adjacent pressurizing chamber 46, that is, thespacing between pressurizing chambers, have a fixed distance, but withat least two different distances. As a result, a predetermined number ofdroplets can be ejected onto a desirable position of an object to besprayed.

FIG. 19 is a sectional view of another embodiment in which thecell-driving-type micro pump member according to the invention isemployed in a liquid discharging device. In the liquid dischargingdevice to which the cell-driving-type micro pump member according to theinvention is used, the procedure for supplying the liquid to thepressurizing chamber is not restricted to those in which the liquidsupplying opening 64 is disposed on the top face as in the liquiddischarging device 40 similar to the conventional ink jet print head.

A liquid discharging device 190, which is shown as an example in FIG.19, has a liquid supplying channel. The liquid discharging device 190 isformed in such a manner that a liquid supplying channel 62 connected toa liquid supplying opening 64 is disposed on the under face of thecell-driving-type micro pump 44, in which the liquid supplying opening64 and a liquid connecting opening 72 are disposed on one surface, e.g.,on the under face of the pressurizing chamber 46, and liquid nozzles 42having a plurality of nozzles for ejecting droplet particles aresuperimposed on each other in such a manner that the nozzle holes areconnected to the pressurizing chamber 46.

Next, methods for manufacturing a cell-driving-type micro pump memberaccording to the invention are described. There are two differentmanufacturing methods due to the difference in the processes forproducing the piezoelectric/electrostrictive elements: Referring toFIGS. 4( a)-4(c), a process in the first method for manufacturing acell-driving-type micro pump member is described in an exemplifiedmanner. In this manufacturing method, a punch and a die are used. Themanufacturing method includes the steps of; punching a predeterminednumber of green sheets 16 made of piezoelectric/electrostrictivematerial with the punch, in which case, slit apertures 25 which becomethe slits 5 after laminating, and slit apertures 15 which become theslits 45 after laminating, are formed in each green sheet as in FIG. 4(a); laminating these green sheets after positioning and providingpiezoelectric/electrostrictive elements having a predeterminedthickness. Then, for instance, as shown in FIG. 4( b), a spacer plate 70which includes the desired slits 5 and slits 45 is formed after firingand unifying; and further forming of electrodes in the slits 5 whichwill become cells, that is, pressurizing chambers. As can be seen inFIGS. 4( a)-4(c), the slit apertures 25, which become the slits 5, canbe punched having a length in the longitudinal direction that is shorterthan the slit apertures 15, which become the slits 45. Then, a coverplate 7, a connection plate 68 and a liquid nozzle member 42 are jointedto the spacer plate 70. In this case, the green sheets 16 can be formedby a known tape-forming means, such as the doctor blade method or thelike.

The positioning of the green sheets in the lamination step can becarried out, either by sequentially superimposing one green sheet onanother inside a frame having substantially the same inner shape as theouter shape of the green sheet, or by passing a guide pin through apre-formed guide hole of the respective green sheets in the laminationprocedure, and then, heating under pressure is carried out.

The manufacturing process shown in FIGS. 3( a)-3(c) corresponds to theprocess in the case that the connection plate 68 is not used, and isidentical with those in FIGS. 4( a)-4(c), except for the above. Theconnection plate 68 prevents reduction of the pressurizing performancefrom the nozzle member by utilizing the connection plate 68 made of sucha material having a higher rigidity, as a metal, ceramic or thickplastic material, when the nozzle member is made of such a materialhaving a lower rigidity as a polyimide film.

As shown in FIGS. 3( a)-3(c), moreover, the cover plate 7 can be formedby a green sheet using the same material, and can be laminated togetherwith the spacer plate 70, the connection plate 68 and the nozzle member42, and then fired and thus unified. Since the cover plate 7 and thespacer plate 70 including the driving parts are simultaneously firedinto a unified ceramic body, a high response micro pump member having anincreased seal durability and an increased cell rigidity can beprovided. In this case, the formation of electrodes is carried out byapplying an electrode paste onto soft green sheets, and precautions mustbe made so as to neither damage nor cause deformation to the greensheets. It is also possible to form electrodes by flowing the electrodepaste and drying it after firing and finishing the cell structure. Inthis case, however, difficult masking work arises, thereby beingrestricted to obtainable electrode patterns. Moreover, after themanufacturing process shown in FIGS. 12( a)-12(c), the process ofbonding it to the liquid nozzle member 42 follows, but the descriptionof the process is omitted.

Next, a second manufacturing method will be described. The secondmanufacturing method substantially follows the first manufacturingmethod, which is shown in FIGS. 4( a)-4(c). The second manufacturingmethod, in which a punch and a die are used, includes the steps ofpunching a predetermined number of green sheets 16 made ofpiezoelectric/electrostrictive material with the punch to form slits;laminating the sheets and then providing piezoelectric/electrostrictiveelements having a predetermined thickness as shown in FIG. 4( a). Afterthat, similarly, for instance, in FIG. 4( b) the spacer plate 70 havingthe required slits 5 and slits 45 is formed after firing and unifying,and then electrodes are formed in the slits 5 which will become thecells, i.e., the pressurizing chambers. In FIG. 4( c), the cover plate7, the connection plate 68 and the liquid nozzle member 42 are joined tothe spacer 70.

The second manufacturing method is different from the firstmanufacturing method with respect to the process in which machining toform both slit apertures 25 which will later become the slits 5 and slitapertures 25 which will become the slits 45 in the green sheets 16 afterlamination, in which case, the lamination is simultaneously carried outwith the aid of a method which will be described later, and thelamination is completed at the end of punching, thus providing thepiezoelectric/electrostrictive elements having a predeterminedthickness.

FIGS. 6( a)-6(e) specifically show a method of simultaneouspunching/lamination in the second manufacturing method, in which a dieassembly consisting of a punch 10 and a die 12 together with a stripper11 arranged at the surrounding thereof to carry out the laminationprocess of green sheets 16 (hereafter, also denoted as sheets) is used.FIG. 6( a) shows a state of laying a first sheet 16 a on the die 12before punching, and in FIG. 6( b) the slits are formed by lowering thepunch 10 and the stripper 11, and then punching the sheet 16 (firststep).

Then, the punching of a second sheet 16 b is started. In this case, thefirst sheet 16 a is moved upwards into tight contact with the stripper11, and removed from the die 12 (second step). The tight contact of thesheets 16 with the stripper 11 can be achieved by evacuating air throughsuction holes formed in the stripper 11.

Moreover, in order to punch the second sheet 16 b, the punch 10 and thestripper 12 are moved upwards from the die 12. In the course of thismovement, it is desirable to move the front end of the punch 10 insidethe slit apertures of the first sheet 16 a, and it is important to stopthe front end at a position slightly withdrawn from the lowest part ofthe first sheet 16 a pulled together (third step). If the punch 10 isreturned to the apertures or if it is completely inserted into thestripper 11, the apertures are deformed due to the softness of thesheets 16, thereby reducing the flatness of the side surfaces of theapertures in the course of forming the slits.

FIG. 6( d) shows the process of punching the second sheet 16 b. Thetight contact of the first sheet 16 a with the stripper 11 permitslaying the second sheet 16 b on the die 12 with ease, and so thepunching is carried out as the step in FIG. 6( b) and at the same time,the second sheet can easily be superimposed on the first sheet 16 a(fourth step).

Repeating the processes in FIG. 6( c) and FIG. 6( d), the first punchedsheet 16 a is superimposed on the second punched sheet 16 b, and aredrawn up together with the stripper 11 (fifth step), thus becoming readyfor punching the third sheet 16 c. In this case, however, it is alsoimportant to stop the front end of the punch at a position slightlywithdrawn from the lowest part of the sheets 16 pulled up together(sixth step). Then, a required number of the sheets 16 are punched andlaminated by repeating the fourth step to the sixth step.

FIG. 6( e) shows the state of punching being finished. After thepunching and laminating of a required number of the sheets 16 isfinished, the holding of sheets 16 with the stripper 11 is released, andthe sheets 16 punched and laminated can be removed from the stripper 11.The removing from the stripper 11 can be securely carried out bydisposing a tool 17 for removing on the under face of the stripper 11,as shown in the drawing. The above-mentioned steps are used in themanufacturing method described in Japanese Patent Application No.2000-280573. A laminated product having a predetermined thickness anddesired number of slits can be provided with the above steps.

FIG. 5( a) shows an end surface of the spacer plate 70 after firing asshown in FIG. 4( b), when the second manufacturing method is employed toobtain the space plate 70 with the simultaneous punching/laminationmethod shown in FIGS. 6( a)-6(e). FIG. 5( b) schematically shows amagnified sectional view of part M on the wall surface of the slit 5shown in FIG. 5( a).

In the method for manufacturing the cell-driving-type micro pump memberaccording to the present invention, slits are formed after firing, sothat the surfaces of the side walls of the slits, which will laterbecome cells, that is, pressurizing chambers, are formed as a firedsurface. When a micro pump member having substantially the samestructure is manufactured with the processes of machining apertures andslits with a dicing unit or the like, after firing thepiezoelectric/electrostrictive material as shown in FIGS. 18( a)-18(e),micro cracks and fractures inside grains as shown in FIG. 9( b) occur,e.g., on the surface of the side walls of the slits. In the method formanufacturing the cell-driving-type micro pump member according to theinvention, such a situation does not occur, and the state of crystalgrains on the surface of the side walls forming the pressurizingchambers indicates that the crystal grains suffering the transgranularfracture are 1% or less, which means substantially zero, so that theproperties are not deteriorated and the durability and reliability canbe enhanced. In addition, the fracture of corner parts (chipping) rarelytakes place during machining, and since the dicing process is not used,it is not necessary to perform cleaning and drying processes.

As an example, the accuracy of superimposing the green sheets in thesecond method for manufacturing the cell-driving-type micro pumpaccording to the invention is a max. of 4 μm regarding the deviationbetween the sheets after firing, in the case of the punched slits havinga width of 50 μm and the slits having a width of 30 μm in the greensheets having a thickness of 50 μm and a Young's modulus of 39 N/mm²,and laminating ten sheets thus treated, and the surface roughness Rt isapproximately 7 μm. As shown in FIG. 5( b), the surfaces of the sidewalls are even and smooth. And the surfaces of the side walls are firedsurfaces, so that no transgranular fracture occurs for the piezoelectriccrystal grain even on the surfaces, and the crystal grains sufferingtransgranular fractures can be reduced to be 1% or less. Furthermore,the width of the slit after firing was approximately 40 μm due toshrinkage during the firing process.

As described above, the slit apertures are formed in the green sheetswith the punch and die and at the same time, laminated, and then thepunch itself is used as an axis for adjusting the position of thelaminated green sheets, thereby preventing the slit apertures machinedby the punch from deformation. Therefore, the slit apertures are notdeformed, and the deviation between the laminated green sheets issuppressed so as to be 5 μm or less, thereby enabling the lamination tobe carried out with high precision, and making it possible to producesmooth wall surfaces of the slits. As a result, slits having a slitwidth of even 70 μm or less and a high aspect ratio of 10-25, said slitsforming the cells, that is, the pressurizing chambers, as well as theslits between the pressurizing chambers can be produced with ease, andthus a micro pump member having excellent properties can be obtained.

Moreover, since neither micro cracks nor fractured particles inside thegrains exist on the surfaces of the side walls, the properties are notdeteriorated due to the residual stress of compression. Since neithertools for moving the sheets nor space for laminating the sheets arerequired, the production line can be simplified, thereby providing a lowcost of production.

In the first and second manufacturing methods, the firing is carried outafter machining the slits, so that the slit width is substantially thesame as the width of punching in the die assembly at the moment ofpunching the sheets. However, the slit is constricted during the firing.Accordingly, thin slits having a width of 40 μm or less can be producedby combining the technique of machining thin slits with the shrinkagedue to the firing. In accordance with the design of a punching dieassembly, for instance, changing the shape of the die assembly, slitshaving a shape other than shapes defined by straight lines can easily beproduced, and an optimal shape adaptable to various applications can beattained, as shown in FIG. 10( c).

Moreover, in the second manufacturing method, it is possible tomanufacture a micro pump member equipped with neither a connection platenor a liquid nozzle member, and also to fire and unify the cover platemade from the same material as that of the spacer plate afterlaminating.

As described above in detail, the present invention solves the problemsin the conventional art, thereby providing a cell-driving-type micropump member on the basis of the piezoelectric/electrostrictive effectand a method for manufacturing the micro pump member, wherein heatingprocesses at a high temperature can be employed; mass production at alow cost is feasible; the cells can be formed to have a slit part otherthan one defined by straight lines, the width of the slit part can be 60μm or less, and a high aspect ratio can be obtained; the operation canbe carried out with a high driving field strength; and a greaterdisplacement and a higher response can be realized with a reduced fieldstrength.

1. A method for manufacturing a cell-driving-type micro pump member witha punch and a die, in which a plurality of cells formed in a base partare used as pressurizing chambers, and side walls of said pressurizingchambers are constituted by piezoelectric/electrostrictive elements, andsaid pressurizing chambers are formed to be independent of adjacentpressurizing chambers, said method comprising the steps of: preparing aplurality of green sheets comprising a piezoelectric/electrostrictivematerial; machining a plurality of slit-shaped apertures correspondingto said plurality of pressurizing chambers and a plurality ofslit-shaped apertures corresponding to a plurality of slits in all ofsaid green sheets with said punch, said slit-shaped aperturescorresponding to said plurality of slits being shorter in a longitudinaldirection than said slit-shaped apertures corresponding to saidplurality of pressurizing chambers; and positioning and laminating allof said green sheets to form piezoelectric/ electrostrictive elementsthat define said side walls of said pressurizing chambers, each of saidside walls of said pressurizing chamber being separated from a side wallof an adjoining pressurizing chamber by one of said slits.
 2. A methodfor manufacturing a cell-driving-type micro pump member with a punch anda die, in which a plurality of cells formed in a base part are used aspressurizing chambers, and side walls of said pressurizing chambers areconstituted by piezoelectric/electrostrictive elements, and saidpressurizing chambers are formed to be independent of adjacentpressurizing chambers, said method comprising the steps of: preparing aplurality of green sheets made of a piezoelectric/electrostrictivematerial, performing a first step for machining first slit apertures ina first green sheet with said punch, a second step for raising saidfirst green sheet into tight contact with a stripper in the state ofsaid punch being not withdrawn from said first slit apertures, and athird step for raising said punch in such a manner that the front end ofsaid punch is withdrawn slightly from the lowest part of said firstraised green sheet, performing a fourth step for machining second slitapertures in a second green sheet with said punch, a fifth step forraising said second green sheet together with said first green sheet inthe state of said punch being not withdrawn from said second slitapertures, and a sixth step for raising said punch in such a manner thatthe front end of said punch is withdrawn slightly from the lowest partof said second green raised sheet, and laminating a plurality of greensheets by repeating the fourth step to the sixth step to formpiezoelectric/electrostrictive elements having a plurality of slits.